The platelet-activating factor acetylhydrolase of mouse platelets.

Platelet-activating factor (PAF) acetylhydrolases are a family of distinct enzymes with the common property of hydrolyzing and inactivating PAF. It has been shown that the structure and the biochemical behavior of these enzymes depend on their cellular origin. We studied the PAF acetylhydrolase activity in mouse platelets in order to investigate the unusual response of these platelets to PAF.

Kinetics of PAF transfer, distribution and metabolism in human blood in vitro.

The transfer kinetics of PAF (0.1-100 nM), deposited as a thin film on a plastic surface, to human blood were studied under conditions of physiological significance. Almost all (83-87%) available PAF was solubilized in two waves.

The mouse plasma PAF acetylhydrolase: II. It consists of two enzymes both associated with the HDL.

The PAF acetylhydrolase (PAF-AH) of mouse plasma was characterised as to its lipoprotein subclass and apolipoprotein association. Association with plasma lipoproteins was established by cholesteryl-hemisuccinate agarose affinity chromatography while electrophoretic and electrofocusing studies demonstrated almost exclusive association with the HDL-VHDL. Fractionation of [4-14C]cholesterol-labelled plasma on a Bio-Gel A-5m column established that 1% of the enzymic activity was associated with the VLDL-LDL, 4.

The mouse plasma PAF acetylhydrolase: I. Characterization and properties.

Mouse plasma platelet-activating factor acetylhydrolase (PAF-AH) has an apparent Km of 7.4 microM and a Vmax of 21.6 nmol/min per mg protein.

In vivo responses of mouse blood cells to platelet-activating factor (PAF): role of the mediators of anaphylaxis.

Intravenous injection of platelet-activating factor (PAF) (0.36 mumol/kg b.w.